A known approach for forming raised S/D regions by EPI growth for FinFet devices is illustrated in FIGS. 1A through 4A and 1B through 4B, with FIGS. 1B through 4B showing cross-sectional views of FIGS. 1A through 4A along cut-lines 1B-1B′ through 4B-4B′, respectively. Adverting to FIGS. 1A and 1B, a plurality of fins 101 are formed on a substrate 103, the fins 101 extending above a shallow trench isolation (STI) layer 105. Next, a dummy polysilicon (poly) gate 201 and a gate hardmask 203, e.g., of silicon nitride (SiN), are formed over the fins 101 and the STI layer 105, as depicted in FIGS. 2A and 2B. Thereafter, gate spacers 301 are formed on each side of the gate 201 and the hard mask 203, as illustrated in FIGS. 3A and 3B. Adverting to FIGS. 4A and 4B, raised S/D regions 401 are formed by EPI growth in a sharp diamond shape on each of the fins 101. Thereafter, although not shown for illustrative convenience, an interlayer dielectric (ILD) layer is formed, the dummy poly gate 201 is removed, a replacement metal gate (RMG) is formed, the ILD is etched, forming a trench, and then a contact is formed in the trench, down to the raised S/D regions 401.
However, an integrated circuit may include both dense narrow Fin pitch devices, as depicted in FIGS. 1A through 4A, as well as isolated single Fin devices. During formation of raised S/D regions by EPI growth, two neighboring narrow Fin pitch raised S/D regions 401 can become merged. Over the merged S/D regions, EPI growth continues in the vertical direction, whereas EPI overgrowth occurs along the angled S/D surfaces for isolated single Fin devices. The EPI-growth rate occurs much faster in the vertical direction than along the S/D surfaces. Consequently, dense narrow pitch FinFet devices will show higher EPI overgrowth than isolated single Fin devices, which can cause contact issues, e.g., threshold voltage mismatch (VTMM).
A need therefore exists for methodology enabling uniform formation of raised S/D regions by EPI growth among both dense narrow Fin pitches and isolated single Fin pitches, with no merged raised S/D regions, and the resulting device.